How can I reset the cursor in the UV Editor with Python?
It is possible to adjust cursor from another context with the following snippet:

import bpy
ob = bpy.context.active_object
for area in bpy.context.screen.areas:
    if area.type == 'IMAGE_EDITOR':   #find the UVeditor
        cursor = area.spaces.active.cursor_location   # get cursor location
        area.spaces.active.cursor_location.x = 0.5*1024;
        area.spaces.active.cursor_location.y = 0.5*1024;


Because you want to normalize in the (0.0,1.0) interval you will have to actually multiply this with the texture size (in my example hardcoded 1024 number).